Frequently surgical operations and other medical procedures and treatments require the intravenous infusion of fluids such as whole blood or whole blood products. The infusion is typically accomplished by an administration set which provides a fluid path between a container of the fluid and a catheter which extends through a patient""s skin and into a vein or artery.
These fluids must be acceptable for infusion upon administration. Although the fluids are generally packaged in a formulation which is appropriate for infusion, filtering of the fluid after the fluid leaves the container but before administration is frequently desired. In particular, whole blood may produce fibrin accumulations and clumped cells during storage which should be removed prior to administration of the whole blood. Thus administration sets for intravenous fluids including blood will typically include a filter element along the flow path established by the administration set.
Generally administration sets include a filter element within a component referred to as a drip chamber. The drip chamber is generally tubular and has an upper end cap and lower end cap attached to opposite ends of a chamber. The upper end cap will contain a means for establishing a fluid connection with the upstream portion of the administration set and the lower end cap will contain a means for establishing a fluid connection with the downstream portion of the administration set. Typically flexible tubing will be connected to the upper and lower end caps; however, other components of the administration set may be directly attached to the end caps. For example, a spike for accessing an administration port of a flexible container of fluid may be attached to the upper end cap.
At the upper end cap is typically a drop former which is designed to produce droplets of a desired volume of the fluid as the fluid flows through the upper end cap and into the chamber. Then by adjusting the flow of fluid so that a desired number of droplets enter the chamber over a certain period of time, a desired rate of volume administration may be accomplished.
A filter element is generally placed within the chamber for filtering the fluid before the fluid exits the chamber. The filter element and chamber walls are generally configured so that all fluid which flows through the chamber must flow through the filter element before the fluid exits the chamber.
In most prior art chambers, the filter is a separate element which must be attached to the other parts of the chamber during assembly. The two most common method of attachment are bonding with either a solvent or adhesive or a press fit. Each option has drawbacks. For example, bonding introduces a bonding agent into the materials which must be acceptable from a clinical standpoint and the bonding step adds cost to the construction of the filtering chamber.
Use of press fit components may make the chamber rigid, and hinder the ability of a health care provider to flex the chamber walls during priming. Also this flexing may contribute to the dislodging of the press fit parts. In addition press fit may require the addition of other parts to insure that the parts are properly attached to each other.
Thus it is an object of the present invention to provide a drip chamber which filters fluid flowing through the chamber and may be economically constructed in a manner which facilitates use by a health care provider. More particularly includes a filtering element which may be attached to the chamber without use of a bonding agent or through a press fit configuration or additional parts.
The present invention generally accomplishes the objectives by providing a filter chamber in which a filter element is attached to a chamber during the molding process of the chamber. More particularly the present invention provides a filter chamber having a chamber which forms a passageway for the flow of fluid through the filter chamber. The filter chamber also includes a filter element and the filter element and chamber are configured and arranged so that a portion and preferably all the fluid flowing through the filter chamber flow through the filter element. The filter element is attached to the chamber during the molding of the chamber. More particularly the filter element is attached to the chamber when the material forming the chamber hardens about one of more portions of the filter element during the molding process of the chamber so that the filter is arranged and supported in the desired position and configuration.